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Data taken 100 years after discovery of galactic cosmic rays

By Laura Snider, Camera Staff Writer

Posted:
08/08/2012 12:41:16 PM MDT

Updated:
08/08/2012 07:34:16 PM MDT

This image, released Wednesday, Aug. 8, 2012, by NASA, shows a mosaic of the first two full-resolution images of the Martian surface from the Navigation cameras on NASA's Curiosity rover. The rim of Gale Crater can be seen in the distance beyond the pebbly ground. The foreground shows two distinct zones of excavation likely carved out by blasts from the rover's descent stage thrusters. (Associated Press)

On Aug. 7, 1912, Austrian physicist Victor Hess took a ride in a hydrogen-filled balloon to an elevation above 17,000 feet over Germany, where he discovered, for the first time, the presence of galactic cosmic rays.

The instruments he brought with him -- three brass-enclosed electroscopes -- showed that there were far more charged particles higher in the atmosphere than lower, meaning that the radiation was coming from space, not from Earth.

Exactly 100 years later, the Boulder-born Radiation Assessment Detector -- which is riding on board the Curiosity rover on Mars -- successfully took the first measurements of galactic cosmic rays, as well as solar energetic particles, from the surface of another planet, said Don Hassler, a researcher at the Southwest Research Institute in Boulder and the principal investigator on the RAD instrument.

"We've learned a lot in the last 100 years since the measurements of Victor Hess," Hassler said Wednesday at a NASA briefing on the Curiosity mission. "We know that there are two types of radiation in space. Galactic cosmic rays and solar energetic particles are driven in large part by the sun."

RAD is designed to collect radiation data that will help scientists better understand how to protect humans from damaging space radiation if they were to travel to Mars in the future.

The instrument has been turned on twice -- first for three and a half hours and then, again, for a five-hour session -- since Curiosity landed on Mars just a few days ago.

"Everything is looking good," Hassler said in an email. "RAD is healthy and working like a champ."

By next week, RAD is expected to be working on its regular schedule, Hassler said, which includes downloading radiation data back to Earth on a daily basis.

Hassler shared a snapshot graph of the raw data so far collected by the instrument at the media briefing. Spikes in the plots indicated where heavy ions had hit the detector, Hassler explained. These heavy ions are one of the things that most interest scientists when they are trying to determine how the health of future Martians might be affected by the incoming radiation.

"What we will achieve with RAD over the next days and months and years will be to characterize and accumulate the statistics and also to gather the energy spectra for each of these heavy ion events," he said.

The Curiosity science team also shared new images taken Wednesday from the newly deployed mast -- which looks like the rover's head and neck. Cameras on the mast have already taken images from every direction, which will be fitted together into a 360-degree panoramic view.

On Wednesday, scientists presented two images that had been merged to show the rim of the Gale Crater, where the rover landed, looking to the north.

"The thing that really struck the science team about the image is you could really be forgiven for thinking NASA pulled a fast one on you and we really put a rover out in the Mojave Desert," said John Grotzinger, project manager of NASA's Mars Science Laboratory mission. "The first impression you get is how Earth-like it seems."

Grotzinger also pointed out alluvial fans in the image, which were presumably created in the past when water worked to erode the mountains along the edge of the crater.

"It's really kind of fantastic to look out across there and see something that has really attracted people to certain parts of Mars for years, wondering, 'What would it look like if you landed on an alluvial fan crated by water?'" Grotzinger said.

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